Method and system for storing and releasing energy through formation fractures

Abstract

The invention relates to a method and a system for storing and releasing energy through formation fractures. The method comprises the following steps: identifying at least one oil-gas-free energy storage formation; hydraulic fracturing construction is conducted on the energy storage stratum, so that at least one stratum fracture is generated in the energy storage stratum; the injection equipment is driven by electric energy to inject high-pressure fluid into the at least one stratum fracture, so that the width of the at least one stratum fracture is increased, and the electric energy is converted into stratum rock elastic deformation energy to be stored; high-pressure fluid in at least one stratum fracture is reversely discharged to the ground to drive an impeller of power generation equipment to rotate for power generation due to the closing process of the stratum fracture, and therefore rock elastic deformation energy stored in the stratum is converted into electric energy again. The energy storage method is low in investment and maintenance cost, can adapt to different earth terrains, and is wide in application range.

Description

[0001] This application is a divisional application of application number 202111292888.7, application date November 3, 2021, and invention name "Method and system for storing and releasing energy through formations". Technical Field

[0002] The present invention relates to the field of underground energy storage, and in particular to a method and system for storing and releasing energy through stratum fractures. Background Art

[0003] Many renewable energy sources, such as solar and wind, have daily and seasonal intermittent output, making them unsuitable for providing baseload power. Consequently, they struggle to directly feed into the grid. Energy storage is crucial for successfully scaling up renewable energy production. Consequently, finding ways to store excess clean electricity on a large scale and reliably transmit it when sunlight and wind are insufficient remains a technological challenge that countries around the world are tackling.

[0004] Currently, large-scale electricity storage methods include lead-acid batteries, lithium-ion batteries, hydrogen fuel cells, compressed air energy storage, and pumped hydro. Lead-acid batteries, lithium-ion batteries, and hydrogen fuel cells have not been widely used due to their high investment and maintenance costs. Pumped hydro involves pumping water from a lower elevation to a higher elevation, converting electrical energy into the water's gravitational potential energy. Therefore, pumped hydro has certain requirements for terrain structure and cannot be applied in relatively flat plains or hilly areas. Compressed air energy storage is a mature energy storage technology, but it requires abandoned mines or underground caverns as gas storage media, so it can only be used in certain specific areas.

[0005] In view of this, there is an urgent need for a new clean electricity storage and release method with low investment and maintenance costs and adaptable to various terrains. Summary of the Invention

[0006] The purpose of the present invention is to provide a method and system for storing and releasing energy through formation fractures, which partially solves or alleviates the above-mentioned deficiencies in the prior art, and has low investment and maintenance costs and a wide range of applications.

[0007] In order to solve the above-mentioned technical problems, the present invention specifically adopts the following technical solutions:

[0008] To partially solve the above technical problems, the first aspect of the present invention is to provide a method for storing and releasing energy through formation fractures, comprising the steps of:

[0009] Identify at least one reservoir formation that does not contain oil or gas;

[0010] Performing hydraulic fracturing on the energy storage formation to generate at least one formation fracture in the energy storage formation;

[0011] Using electrical energy to drive an injection device to inject a high-pressure fluid into the at least one formation fracture, thereby increasing the width of the formation fracture, thereby converting the electrical energy into elastic deformation energy of the formation rock for storage;

[0012] The high-pressure fluid discharged during the closing process of the formation fracture is used to drive a preset power generation device to generate electricity, thereby converting the elastic deformation energy of the formation rock into electrical energy for energy release.

[0013] In some embodiments of the present invention, the fracturing fluid in the hydraulic fracturing operation includes a fluid loss control agent.

[0014] In some embodiments of the present invention, the fluid loss agent includes: at least one high molecular polymer, and / or at least one resin, and / or at least one quartz sand, and / or at least one gel, and / or at least one silicate, and / or at least one sulfate, and / or at least one phosphate, and / or at least one oxalate, and / or at least one particle having the effect of plugging the pores of the rock matrix of the formation.

[0015] In some embodiments of the present invention, before the step of injecting high-pressure fluid into the at least one formation fracture, the method further comprises the following steps:

[0016] Calculating a three-dimensional shape of the formation fracture according to a hydraulic fracturing model, rock mechanical properties, and a first construction parameter, and obtaining an expansion radius of the formation fracture according to the three-dimensional shape;

[0017] It is determined whether the expansion radius is equal to or greater than the target radius, and when the expansion radius of the formation fracture is equal to or greater than the target radius, the hydraulic fracturing construction is stopped.

[0018] In some embodiments of the present invention, the pressure of the fluid injected into the at least one formation fracture is greater than the minimum principal stress of the formation and less than the expansion pressure of the formation fracture, so that the width of the formation fracture gradually increases.

[0019] In some embodiments of the present invention, before utilizing the high-pressure fluid discharged during the closure of the formation fracture to drive a preset power generation device to generate electricity, the method further includes the following steps:

[0020] Determine whether the width of at least one of the formation fractures is equal to or greater than a preset target width. If so, stop supplying power to the injection device so that the injection device stops injecting the high-pressure fluid into the at least one formation fracture.

[0021] In some embodiments of the present invention, before injecting high-pressure fluid into the at least one formation fracture, the method further includes the step of providing at least one water reservoir underground or on the ground for storing the fluid.

[0022] In some embodiments of the present invention, the step of using the high-pressure fluid discharged during the closure of the formation fracture to drive a preset power generation device to generate electricity specifically includes the following steps:

[0023] Monitor whether there is a demand for power generation, and when it is detected that there is a demand for power generation, open the control valve on the reverse flow pipe connecting the wellbore corresponding to the formation fracture to the ground, so that the high-pressure fluid in the formation fracture is reversed to the ground through the reverse flow pipe and drives the power generation equipment to generate electricity; otherwise, continue to monitor whether there is a demand for power generation.

[0024] In some embodiments of the present invention, the high-pressure fluid includes: a bactericide, and / or a descaling agent, and / or a mineral salt, and / or a fluid loss agent.

[0025] In a second aspect, the present invention further provides a system for storing and releasing energy through formation fractures, comprising:

[0026] a formation identification device for identifying at least one energy storage formation that does not contain oil or gas;

[0027] A hydraulic fracturing construction device, used for performing hydraulic fracturing construction on the energy storage formation, so that at least one formation fracture is generated in the energy storage formation;

[0028] an injection device for injecting high-pressure fluid into the at least one formation fracture to increase the width of the at least one formation fracture, thereby converting electrical energy into elastic deformation energy of the formation rock for storage;

[0029] A power generation device is used to convert the elastic deformation energy of the formation rock into electrical energy under the drive of the high-pressure fluid when the high-pressure fluid in the formation fracture is reversed under the action of rock compression during the closing process of the formation fracture.

[0030] In some embodiments of the present invention, the system further comprises:

[0031] A water reservoir for storing the high-pressure fluid, wherein the water reservoir is connected to the wellbore corresponding to the formation fracture via a reverse flow pipe, and a control valve is provided in the wellbore or the reverse flow pipe;

[0032] A monitoring device is connected to the control valve and is used to monitor whether there is a current demand for power generation. When a demand for power generation is detected, a first control instruction indicating opening the control valve is generated and sent to the control valve, so that the wellbore is connected to the water reservoir through the reverse flow pipe; otherwise, the monitoring device continues to monitor whether there is a demand for power generation.

[0033] Beneficial Effects: The present invention identifies at least one oil- and gas-free energy storage formation and then hydraulically fractures the identified formation, creating at least one formation fracture within the formation. Electric energy is then used to drive an injection device to inject high-pressure fluid into the formation fracture, widening the fracture. This converts the electrical energy into elastic deformation energy of the formation rock for storage, thereby achieving energy storage with low investment and maintenance costs. The electrical energy in these steps is derived from renewable energy sources such as wind power or solar power.

[0034] Furthermore, as the formation cracks gradually close, due to the squeezing effect of the formation rocks, the high-pressure fluid in the cracks is discharged back to the ground to drive the preset power generation equipment to generate electricity, that is, the elastic deformation energy of the formation cracks is converted into electrical energy, thereby achieving stable power supply in the case of insufficient solar energy or wind energy.

[0035] The method and system of the present invention can convert the electrical energy generated by sunlight or wind into rock elastic deformation energy for storage when there is sufficient sunlight or wind, and release the electrical energy to the power grid when needed, which is of great significance for the peak regulation of wind power generation or solar power generation connected to the grid.

[0036] The present invention can be applied to underground porous and permeable rock formations, such as shale formations, carbonate formations, sandstone formations, etc. Among them, since shale has a wide distribution range and many types, and is deposited in both terrestrial and marine basins, shale formations are applicable to a wide range of areas as energy storage formations and are not restricted by surface terrain conditions; on the other hand, since the permeability of shale formations is extremely low, when high-pressure fluid is stored in the formation cracks, only a very small amount of high-pressure fluid will be lost to the pores of the formation rock, that is, the shale formation can store the high-pressure fluid in the formation cracks for a long time, which means that the shale formation has a high energy storage efficiency; in addition, since this method can be used for shale formations that do not contain oil and gas and are buried at a depth of only a few hundred meters, the construction difficulty is small, and the investment and maintenance costs are low.

[0037] The method disclosed in the present invention also involves hydraulic fracturing. As a mature technology in the field of oil and gas, hydraulic fracturing has been used on a large scale. Therefore, related construction supporting equipment is easy to obtain and the cost is controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the embodiments or the description of the prior art. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the various elements or parts are not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without inventive work.

[0039] Figure 1 is a flow chart of a method for storing and releasing energy through formation fractures in an exemplary embodiment of the present invention;

[0040] Figure 2 It is a schematic diagram of the system for hydraulic fracturing vertical wells and horizontal wells;

[0041] Figure 3A is a schematic diagram of an example embodiment of the present invention wherein an electric injection device injects fluid from a reservoir into a formation fracture in a shale formation;

[0042] Figure 3B It is a schematic diagram of discharging high-pressure fluid in a formation fracture back into a water reservoir and driving a power generation device to generate electricity in an exemplary embodiment of the present invention;

[0043] Figure 4A is a schematic diagram of an electric injection device injecting fluid from a water reservoir into a formation fracture in a shale formation in another exemplary embodiment of the present invention;

[0044] Figure 4B is a schematic diagram of another exemplary embodiment of the present invention, in which high-pressure fluid in a formation fracture is discharged back into a water reservoir to drive a power generation device to generate electricity;

[0045] Figure 5 Schematic diagram of a system for storing and releasing energy through a formation in an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0046] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0047] Herein, suffixes such as "module," "component," or "unit" used to represent elements are only used to facilitate description of the present invention and have no specific meaning. Therefore, "module," "component," or "unit" may be used interchangeably.

[0048] The term "fluid" as used herein may include, but is not limited to, a gas, a liquid, an emulsion, a slurry, and a flow of solid particles having flow characteristics similar to that of a liquid. For example, the fluid may include a water-based liquid with chemical additives. Furthermore, the chemical additives may include, but are not limited to, acids, gels, potassium chloride, surfactants, and the like.

[0049] The "stratum" or "reservoir" herein refers to an underground porous and permeable rock formation (e.g., shale formation, sandstone formation, carbonate formation, etc.) that can serve as a storage space for fluids. Typically, these fluids can be water, hydrocarbons, or gases. In this article, such porous and permeable rock formations that can store high-pressure fluids are collectively referred to as "energy storage formations." Shale formations are used as a preferred embodiment herein to illustrate the energy storage and release methods and systems of this application, as they can store fluids in their internal cracks for a long time.

[0050] The term "hydraulic fracturing" or "fracture" or "cracking" as used herein refers to the generation and expansion of cracks in formation rocks under the action of external forces (such as high-pressure fluid).

[0051] "Hydraulic fractures" or "formation fractures" or "fractures" herein are open gaps in rock created within a formation after hydraulic fracturing operations, and the terms "hydraulic fractures" or "formation fractures" or "fractures" are used interchangeably.

[0052] The term "bottom-hole pressure" used herein refers to the pressure at or near the initiation depth of a hydraulic fracture (formation fracture) within a wellbore. When friction losses are negligible, the bottom-hole pressure is equal to the fracture pressure of the hydraulic fracture.

[0053] As used herein, a "wellbore" refers to a hole drilled or inserted into a formation. Typically, a wellbore is cylindrical, and therefore may have a circular cross-section. However, a wellbore may have any other cross-section. A wellbore may be open-hole, or cased, where casing is cemented to the inner wall of the wellbore.

[0054] The "width of a formation fracture" or "fracture width" in this article refers to the relative displacement distance between the two walls in the direction perpendicular to the fracture surface. When the formation fracture is assumed to be circular (or in engineering practice, the formation fracture can be considered to be circular or approximately circular), the "expansion radius" of the formation fracture refers to the radius of the circle (see Figure 3A The terms "width of formation fractures" or "fracture width" are interchangeable.

[0055] The term "constant" or "unchanged" as used herein does not mean that the absolute change of the specified item is zero, but rather that the change of the specified item is very small, and in engineering practice, the item can be considered to remain constant. For example, the term "constant bottom hole pressure" as used herein also means "approximately constant bottom hole pressure", or, the term "constant expansion radius" as used herein actually means that the "expansion radius" of the formation fracture "essentially remains unchanged" or "approximately constant" under the action of high-pressure fluid, or, the term "constant width of the formation fracture" as used herein actually means that the "width of the formation fracture" "essentially remains unchanged" or "approximately constant" under the action of high-pressure fluid. It should also be recognized that the term "equal / equal to" as used in this disclosure does not mean that the specified items are exactly the same, but rather is used to specify two items that have negligible differences in engineering practice. For example, the term "equal / equal to" as used in this disclosure can also mean "approximately equal / equal to".

[0056] Example 1

[0057] Shale is widely distributed and has extremely low permeability. In the field of oil and gas, shale formations are generally regarded as the overlying sealing layer of conventional oil and gas reservoirs, which can prevent oil and gas from migrating upward and volatilizing to the ground. At the same time, the shale formation itself can also be used as a fluid storage medium. Due to the extremely low permeability of the shale formation, high-pressure fluids in the internal formation cracks can be stored for a long time, and only a very small amount of fluid will be lost to the pores of the formation rock. For example, the Oak Ridge National Laboratory in the United States has injected radioactive fluid waste into artificial formation cracks in shale formations for decades to achieve the purpose of permanent preservation. Therefore, preferably, the present invention achieves the purpose of long-term energy storage by storing high-pressure fluids in artificial cracks in porous and permeable shale formations (i.e., formation cracks formed by hydraulic fracturing construction), that is, using shale formations as energy storage formations. Of course, the present invention can also be applied to other porous and permeable rock formations.

[0058] See also Figure 1 , the present invention provides a method for storing and releasing energy through formation fractures.

[0059] In step S100, at least one energy storage formation (ie, reservoir) that does not contain oil or gas is identified.

[0060] In some embodiments, the energy storage formations containing no oil or gas include depleted oil and gas formations.

[0061] In some embodiments, intuitive methods can be used to identify relevant information about the energy storage formation (preferably a shale formation) (e.g., burial depth and thickness of the formation), for example, by obtaining cores from a well. In other embodiments, indirect methods can be used to identify relevant information about the formation, for example, by interpreting well logging data and seismic data inversion.

[0062] In step S102, hydraulic fracturing is performed on the energy storage formation to generate at least one formation fracture in the energy storage formation.

[0063] During hydraulic fracturing, the injected fracturing fluid is pumped into the wellbore through surface facilities, such as Figure 2 The fracturing fluid is pumped into the vertical well 210 and the horizontal well 220 respectively through the first surface facility 240 and the second surface facility 250. Once the bottom hole pressure of the vertical well 210 and the horizontal well 220 reaches the fracture pressure of the underground rock formation 230 (i.e., the energy storage formation) (i.e., the bottom hole pressure is greater than or equal to the fracture pressure), the first hydraulic fracture 260 and the second hydraulic fracture 262 in the vertical well 210 will fracture from around the vertical well 210 and expand into the underground rock formation 230 until the pumping stops (i.e., the hydraulic fracturing construction stops). Correspondingly, the third hydraulic fracture 264, the fourth hydraulic fracture 266, the fifth hydraulic fracture 268, and the sixth hydraulic fracture 270 in the horizontal well 220 will fracture from around the horizontal well 220 and expand into the underground rock formation 230 until the pumping stops. Figure 2 As shown, hydraulic fractures (e.g. Figure 2 The first hydraulic fracture 260, the third hydraulic fracture 264, and the fourth hydraulic fracture 266 in the shale formation can form a planar geometry and extend in a direction perpendicular to the minimum principal stress F of the shale formation. However, under certain geological conditions, some hydraulic fractures (e.g., Figure 2 The second hydraulic fracture 262, the fifth hydraulic fracture 268, and the sixth hydraulic fracture 270) can interact with pre-existing natural fractures to form complex fracture geometries.

[0064] In practical applications, the expansion degree of formation fractures can be determined according to different energy storage requirements and the mechanical properties of the energy storage formation. For example, if more energy needs to be stored, a longer formation fracture needs to be designed. If relatively less energy needs to be stored, a shorter formation fracture needs to be designed. Therefore, the design parameters of the formation fractures, such as the expansion radius (or expansion length), can be set in advance according to actual needs. When it is determined that the expansion radius of the formation fractures reaches the design requirements, the pumping of fracturing fluid is stopped (that is, the hydraulic fracturing construction is stopped), so that the formation fractures gradually stop expanding.

[0065] In some embodiments, before the step of injecting high-pressure fluid into at least one formation fracture (i.e., before executing step S104), the following steps are further included:

[0066] It is determined whether the expansion radius of the formation fracture reaches a preset target radius, and when it is determined that the expansion radius of the formation fracture reaches the target radius, the hydraulic fracturing construction is stopped, so that the formation fracture gradually stops expanding.

[0067] Specifically, in some embodiments, the step of determining whether the expansion radius of the formation fracture reaches a preset target radius specifically includes the steps of: calculating the three-dimensional shape of the formation fracture based on a pre-constructed hydraulic fracturing model, rock mechanical properties, and first construction parameters, and obtaining the expansion radius of the formation fracture based on the three-dimensional shape; then, determining whether the expansion radius of the formation fracture is equal to or greater than the target radius.

[0068] In some embodiments, the hydraulic fracturing model may adopt a two-dimensional PKN model, a KGD model, a RADIAL model, a pseudo-three-dimensional model, and a full three-dimensional model. The first construction parameter is the construction parameter of the surface facilities (i.e., the injection equipment in the hydraulic fracturing construction device), including: the injection rate of the fracturing fluid, the total injection volume, and the viscosity of the fracturing fluid.

[0069] Of course, in other embodiments, when to stop hydraulic fracturing construction can be determined by the staff based on relevant work experience. For example, the staff can determine or calculate the time to stop hydraulic fracturing construction based on work experience, combined with the injection rate, total injection volume and viscosity of the fracturing fluid.

[0070] Preferably, in some embodiments, the preset target radius is set by professional technicians based on the mechanical properties of the energy storage formation, while ensuring that the formation fractures have a certain storage capacity, while avoiding the expansion radius of the formation fractures being too large to cause damage to the energy storage formation.

[0071] In some embodiments, multiple formation fractures are created during hydraulic fracturing. To prevent excessive expansion radius of the formation fractures, which could damage the energy storage formation, hydraulic fracturing is preferably stopped when a formation fracture is detected with an expansion radius equal to or greater than a preset target radius. Alternatively, hydraulic fracturing may be stopped when the average expansion radius of all formation fractures is determined to be equal to or greater than the preset target radius.

[0072] It is understandable that when hydraulic fracturing construction is stopped, the formation fractures will not stop expanding immediately. Only when the fluid pressure in the formation fractures tends to be balanced with the fracture pressure, that is, when the fluid pressure is less than the fracture pressure, the formation fractures will stop expanding. Therefore, in order to avoid the expansion radius of the formation fractures being too large, preferably, in some embodiments, when the expansion radius of the formation fractures is approximately equal to (or close to) the target radius (for example, expansion radius = target radius × 0.90-0.95), the hydraulic fracturing construction is stopped.

[0073] Preferably, in order to reduce the rate of leakage of the fracturing fluid in the formation fractures into the surrounding rocks, so that the formation fractures in the energy storage formation have the ability to store fracturing fluid or high-pressure fluid for a long time, in some embodiments, a fluid loss preventer is added to the fracturing fluid in the hydraulic fracturing construction in step S102.

[0074] Preferably, in some embodiments, the fluid loss agent may include: at least one high molecular polymer, and / or at least one resin, and / or at least one gel and other additives. After the fluid loss agent is injected into the formation fracture, it covers the surface of the formation fracture to form a cap layer with an extremely low leakage rate. In addition, the fluid loss agent may also be particles that have the effect of plugging the pores of the rock matrix of the energy storage formation, such as micro-nano materials. During the fluid loss process, the particles fill the pores of the rock matrix around the formation fracture, reducing the permeability of the energy storage formation and achieving a fluid loss prevention effect.

[0075] In some embodiments, the fluid loss agent may include: at least one silicate, and / or at least one sulfate, and / or at least one phosphate, and / or at least one oxalate. The silicates, sulfates, phosphates, and oxalates may react with formation mineral cations to generate precipitates that plug the pores of the formation rock matrix.

[0076] In step S104, electric energy is used to drive an injection device to inject high-pressure fluid into at least one formation fracture, so that the width of the at least one formation fracture increases, thereby converting the electric energy into elastic deformation energy of the formation rock for storage.

[0077] Furthermore, in some embodiments, in step S104, the pressure of the fluid injected into at least one formation fracture is greater than the minimum principal stress of the energy storage formation and less than the expansion pressure of the formation fracture, so that the width of the formation fracture gradually increases, and the expansion radius remains unchanged or constant (because the fluid pressure is less than the expansion pressure of the formation fracture, the formation fracture will not expand, that is, the expansion radius of the fracture remains unchanged or constant).

[0078] Of course, in other embodiments, the expansion radius of a formation fracture remaining unchanged or constant can be understood as remaining unchanged or constant over a period of time. For example, when the width of a formation fracture changes due to the action of a high-pressure fluid, its expansion radius will also gradually change (i.e., continue to expand), but within a certain period of time (e.g., one hour), the change in the expansion radius can be negligible in engineering practice; or, when a formation fracture expands due to the action of a high-pressure fluid, after a certain period of time, particles added to the high-pressure fluid will fill or partially fill the continuing expansion fracture.

[0079] Preferably, in some embodiments, the minimum principal stress of the energy storage formation can be obtained through a diagnostic fracturing injection test or a rapid injection flowback test. The propagation pressure of the formation fracture can be obtained by analyzing the instantaneous shut-in pressure (ISP) of the pressure drop curve after pump shutdown during hydraulic fracturing.

[0080] In some embodiments, step S104 specifically includes the steps of: monitoring the injected fluid pressure in real time, and determining whether the injected fluid pressure is greater than the minimum principal stress of the formation and less than the expansion pressure of the formation fracture;

[0081] If so, maintain the second construction parameter for injecting high-pressure fluid into the formation fracture; otherwise, adjust the second construction parameter for injecting high-pressure fluid into the formation fracture (i.e., the construction parameter of the injection equipment) so that the current fluid pressure is always maintained between the expansion pressure and the minimum principal stress of the energy storage formation.

[0082] In some embodiments, the second construction parameter includes: the injection rate and the total injection volume of the fluid. Specifically, the fluid pressure can be adjusted by adjusting the injection rate of the high-pressure fluid or the amount of fluid injected by the injection equipment, and the fluid pressure can be monitored by a pre-installed pressure monitoring device.

[0083] Specifically, in some embodiments, before injecting high-pressure fluid into at least one formation fracture (i.e., before executing step S104), the method further includes the step of providing at least one reservoir underground or on the surface for storing the fluid. The reservoir is connected to the wellbore being hydraulically fractured via a pipeline (e.g., a surface pipeline).

[0084] Preferably, in some embodiments, one or more additives may be added to the fluid in the reservoir in advance (that is, one or more additives may be added to the fluid injected into the formation fractures), for example, bactericides, descaling agents, mineral salts (such as KCl, NaCl, CaCl2, NaSiO4, etc.) and fluid loss preventers, wherein the mineral salts are used to balance the electrolytes in the energy storage formation.

[0085] When the water reservoir is set on the ground, preferably, in order to reduce the loss of fluid, in some embodiments, the water reservoir is provided with a shielding structure for preventing the evaporation of the fluid, for example, a plastic or metal film is covered above the water reservoir.

[0086] In step S106, it is determined whether the width of at least one formation fracture is equal to or greater than a preset target width. If so, step S108 is executed, i.e., supplying electrical energy to the injection device is stopped so that the injection device stops injecting high-pressure fluid into at least one formation fracture, thereby maintaining the bottom hole pressure unchanged and making the width of the formation fracture unchanged (at this time, since the pipelines between the wellbore and the water reservoir and the injection device are all in a closed state, the bottom hole pressure remains unchanged after the injection of high-pressure fluid is stopped); otherwise, step S110 is executed to continue injecting high-pressure fluid into at least one formation fracture.

[0087] Among them, the width of the formation fracture is calculated based on the height of the formation fracture, the expansion radius of the formation fracture and the bottom hole pressure. It can be understood that the widths at different positions in the formation fracture are not equal. Preferably, in some embodiments, the "width of the formation fracture" in step S106 refers to the average width of all formation fractures; of course, in other embodiments, the "width of the formation fracture" in step S106 may also refer to the width of any formation fracture.

[0088] For example, in some embodiments, during the process of injecting high-pressure fluid into formation fractures, width data of all formation fractures are obtained, and the widths of all formation fractures are averaged to obtain an average width of all formation fractures. When the average width is equal to or greater than a preset target width, power is stopped to the injection device, so that the injection device stops injecting high-pressure fluid into the formation fractures.

[0089] In some embodiments, the target width of the formation fracture is pre-set by professionals based on the mechanical properties of the energy storage formation and different energy storage requirements. This ensures that the formation fracture has a certain storage capacity while preventing damage to the energy storage formation caused by excessive width of the formation fracture. It is understood that due to the presence of multiple formation fractures, to avoid damage to the energy storage formation caused by excessive width of the formation fracture, preferably, when it is detected (or determined) that the width of a formation fracture is equal to or greater than the preset target width, step S108 is executed to stop supplying power to the injection device, so that the injection device stops injecting high-pressure fluid into the at least one formation fracture, thereby maintaining the bottomhole pressure constant and the fracture width constant.

[0090] Of course, in other embodiments, when it is monitored that the power supplied to the injection equipment is insufficient (for example, weather changes cause insufficient supply of solar or wind power generation, specifically, when all or most of the solar and wind power generation is consumed by the end users of the power supply, and there is no excess power to supply the injection equipment), step S108 is executed to stop supplying power to the injection equipment, so that the injection equipment stops injecting high-pressure fluid into at least one formation fracture, thereby maintaining the bottom hole pressure unchanged and the fracture width unchanged.

[0091] For example, in some embodiments, see Figure 3A and Figure 3B When the power supply to the injection device is stopped so that the injection device stops injecting high-pressure fluid into at least one formation fracture, the control valve corresponding to the first ground pipeline 330 (i.e., the injection pipeline for injecting high-pressure fluid) is closed at the same time (at this time, since the control valve corresponding to the second ground pipeline 370, i.e., the return pipeline for high-pressure fluid return, is in a normally closed state), the high-pressure fluid in the formation fracture and the wellbore cannot be returned to the water reservoir / ground through the first and second ground pipelines. At this time, the total volume of the high-pressure fluid in the formation fracture and the wellbore remains unchanged (the filtration loss of the high-pressure fluid can be ignored in engineering practice), thereby maintaining the bottom hole pressure unchanged and making the width of the formation fracture remain unchanged.

[0092] In step S112, whether there is a demand for power generation is monitored, and when it is detected that there is a demand for power generation, step S114 is executed, and the high-pressure fluid discharged due to the closure of at least one formation fracture is used to drive the preset power generation equipment to generate electricity, thereby converting the elastic deformation energy of the formation rock into electrical energy; otherwise, continue to monitor whether there is a demand for power generation.

[0093] Furthermore, in some embodiments, the water reservoir is connected to the wellbore corresponding to the formation fracture through a pipe (for example, an injection pipe and a backflow pipe), and when the injection of high-pressure fluid into the formation fracture is stopped, the backflow pipe and the injection pipe are both in a closed state (specifically, the control valves in the backflow pipe and the injection pipe are in a closed state). Therefore, when the demand for power generation is detected, the control valve corresponding to the backflow pipe is opened to allow the backflow pipe to circulate, so that the high-pressure fluid in the formation fracture can be discharged back into the water reservoir through the backflow pipe under the action of rock squeezing, and at the same time drive the power generation equipment to generate electricity.

[0094] For example, see Figure 3A and Figure 3B , the first surface pipeline 330 (i.e., the injection pipeline) and the second surface pipeline 370 (i.e., the backflow pipeline) connecting the water reservoir and the wellbore are both provided with control valves for controlling the circulation and closure of the surface pipelines, and after the injection of high-pressure fluid into the formation fracture is stopped and before the need for power generation is detected, the control valve corresponding to the first surface pipeline is in a closed state. When the need for power generation is detected (for example, the corresponding control system, or the first power generation equipment, or the corresponding staff receives a power supply request from the outside, such as the power grid or other control system), the control system connected to the control valve, or The first power generating device 360 opens the control valve corresponding to the second surface pipeline 370 between the wellbore and the water reservoir (of course, it can also be opened manually by the staff), thereby connecting the wellbore and the water reservoir. Then, under the action of rock squeezing, the high-pressure fluid in the formation cracks is discharged back into the water reservoir, and drives the impeller of the first power generating device 360 to rotate to generate electricity; of course, if no power supply request is received, the second surface pipeline 370 between the wellbore and the water reservoir will always remain closed, that is, the control valve in the second pipeline is in a normally closed state. At this time, continue to monitor whether there is a power supply demand.

[0095] Furthermore, by connecting the power generation equipment to the power grid, stable power supply to electrical equipment can be achieved.

[0096] Specifically, in some embodiments, at least one power generation device is pre-installed in a reservoir or in a pipeline connecting the reservoir to a wellbore, and the power generation device is connected to a power grid. After the injection of high-pressure fluid into the formation fracture ceases, and the pipeline between the reservoir and the wellbore is open (or flowing), the fluid pressure within the formation fracture (greater than the minimum principal stress of the formation and less than the formation fracture expansion pressure) is significantly higher than the water pressure within the reservoir due to rock compression. Consequently, the high-pressure fluid in the formation fracture is reversed into the reservoir under the action of rock compression, driving the impeller of the power generation device to rotate and generate electricity. This converts the elastic deformation energy of the rock surrounding the formation fracture into electrical energy, thereby achieving stable power supply to the power grid connected to the power generation device. As the formation fracture gradually closes, the fluid pressure within the formation fracture gradually decreases. When the formation fracture is completely closed, the fluid pressure within the formation fracture drops to the minimum principal stress of the formation, and the elastic deformation energy of the rock surrounding the formation fracture is fully released. In other words, the elastic deformation energy of the rock is fully converted into electrical energy (ignoring friction losses during the movement of the high-pressure fluid in the surface pipeline and wellbore).

[0097] In some embodiments, when a power demand is detected, a control valve disposed on a pipeline between the wellbore and the reservoir may be opened, thereby causing the fluid in the formation fracture to be reversed under the action of rock squeezing and drive the power generation equipment to generate electricity. Figure 4A and Figure 4B After stopping the injection of high-pressure fluid into at least one formation fracture, the valve in the third surface pipeline 430 between the wellbore and the water reservoir is also in a closed state (at this time, the injection pipeline and the return pipeline are the same pipeline, namely the third surface pipeline 430). When it is detected that power generation is required, the control valve corresponding to the third surface pipeline 430 between the wellbore and the water reservoir is opened. At this time, under the action of rock squeezing, the high-pressure fluid in the formation fracture is returned into the water reservoir through the third surface pipeline 430, and drives the impeller of the second power generation device 410 (ie, the second injection device) to rotate to generate electricity; if no power supply demand is detected, the surface pipeline 430 between the wellbore and the water reservoir is always kept closed (specifically, the control valve corresponding to the third surface pipeline is closed).

[0098] The cyclic storage and release of electric energy can be achieved through the reciprocating cycle of steps S104, S106, S108, S112 and S114. For example, during the day, excess solar power is stored as the elastic deformation energy of the rocks around the cracks in the energy storage formation. At night, when solar power generation is impossible, the elastic deformation energy of the energy storage formation is converted into electric energy and released to the power grid for power supply. Of course, the electric energy can also come from wind power generation or other renewable resources.

[0099] Example 2

[0100] For example, in one embodiment disclosed in the present invention, Figure 3A As shown, the grid-powered first injection device 310 (i.e., electric injection device) injects the fluid in the first water reservoir 320 into the seventh hydraulic fracturing crack 380 in the first shale formation 350 through the first surface pipeline 330 and the first wellbore 340, so that the width of the formation crack expands and the rock around the crack undergoes elastic deformation to store energy.

[0101] It is assumed that the formation fracture is circular (or in engineering practice, the formation fracture can be considered to be circular or approximately circular), and the expansion radius of the circular fracture is 500m (the expansion radius is as follows Figure 3A As shown by the double-headed arrow R), 500 meters above the ground, the average Young's modulus of the rock is 20 GPa, and the fluid pressure in the fracture is 3 MPa higher than the minimum principal stress of the shale formation. According to fracture mechanics, the energy stored in the elastic deformation of the shale formation around the fracture can be calculated to be 2.8×10 11 J, that is, 78530kw·h. After stopping the injection of fluid into the fracture and detecting the need for power generation, Figure 3B As shown, the seventh hydraulic fracturing crack 380 in the shale formation 350 gradually closes and squeezes the fluid in the crack, so that the fluid (i.e., high-pressure fluid) is discharged back into the first water reservoir 320 through the first wellbore 340 and the second surface pipeline 370, thereby driving the impeller of the first power generation equipment 360 to rotate and generate electricity, and the electricity is fed into the power grid.

[0102] Example 3

[0103] Preferably, in order to simplify the construction device, in some embodiments, the power generation equipment and the injection equipment are the same equipment, and the injection equipment is set in the ground pipeline. When the power grid is connected, the injection equipment (i.e., the power generation equipment) starts to work. At this time, the ground pipeline between the wellbore and the water reservoir and the injection equipment is in an open state / flow state (specifically, the control valve set in the wellbore or the ground pipeline is opened), and the impeller of the injection equipment drives the fluid in the water reservoir to flow through the ground pipeline into the wellbore, so that at least one formation crack created by hydraulic fracturing construction becomes wider, that is, the electrical energy is converted into the elastic deformation energy of the formation crack. When at least one formation crack is detected / judged When the width of the formation crack is greater than or equal to the target width, the injection equipment stops injecting fluid into the wellbore and places the ground pipeline between the wellbore, the water reservoir and the injection equipment in a closed state / non-circulating state (specifically, close the control valve set in the ground pipeline or the wellbore), so that the bottom hole pressure remains unchanged and the width of the formation crack remains unchanged. When the demand for power generation is detected, the control valve corresponding to the ground pipeline is opened. Under the squeezing action of the rock, the high-pressure fluid in the formation crack is gradually discharged back into the water reservoir through the wellbore and the bottom pipeline. In this process, the reversed fluid drives the impeller of the injection equipment to rotate to generate electricity, and the crack gradually closes.

[0104] For example, in one embodiment disclosed in the present invention, Figure 4A As shown, the grid powers the second injection device (i.e., the second power generation device, i.e., the electric injection device) 410 to inject the fluid in the reservoir 420 through the third surface pipeline 430 and the second wellbore 440 into the eighth hydraulic fracture 460 in the second shale formation 450, causing the fracture width to expand and the rock around the fracture to elastically deform and store energy. Figure 4B As shown, when the eighth hydraulic fracture 460 in the second shale formation 450 closes, the fluid within the fracture is squeezed. This causes the fluid (i.e., high-pressure fluid) to flow back from the eighth hydraulic fracture 460, through the second wellbore 440 and the third surface pipeline 430, into the second reservoir 420, driving the impeller of the second injection device 410 to rotate and generate electricity, which is then fed into the power grid.

[0105] Preferably, in some embodiments, to prevent hydraulic fractures (i.e., formation fractures) from initiating and propagating in other non-shale formations, the method further comprises the step of: placing casing in the wellbore above the energy storage formation. Specifically, it is generally necessary to cement the casing in the open hole wellbore to the upper portion of the identified burial depth of the energy storage formation.

[0106] Preferably, to facilitate the initiation of hydraulic fracturing fractures within the identified energy storage formation, in some embodiments, the step of hydraulically fracturing the energy storage formation further includes the step of perforating the wellbore within the energy storage formation where the wellbore under hydraulic fracturing is located. Specifically, the perforating operation can be performed within the thickness of the identified energy storage formation (i.e., within the upper and lower boundaries of the burial depth of the energy storage formation).

[0107] Preferably, in some embodiments, the fluid loss agent in the fluid or fracturing fluid includes: at least one high molecular weight polymer, and / or at least one resin, and / or at least one quartz sand, and / or at least one gel, and / or at least one silicate, and / or at least one sulfate, and / or at least one phosphate, and / or at least one oxalate, and / or at least one particle having the effect of plugging the pores of the rock matrix of the energy storage formation.

[0108] Example 4

[0109] The present invention also provides a system for storing energy in formation fractures, see Figure 5 , the device comprises:

[0110] a formation identification device 02, for identifying at least one energy storage formation that does not contain oil or gas;

[0111] A hydraulic fracturing device 04 is used to perform hydraulic fracturing on the energy storage formation, so as to generate at least one formation fracture in the energy storage formation;

[0112] The injection device 06 is used to inject high-pressure fluid into at least one formation fracture, so that the width of the at least one formation fracture increases, thereby converting electrical energy into elastic deformation energy of the formation rock for storage.

[0113] Preferably, in some embodiments, the hydraulic fracturing construction device 04 and the injection device 06 are the same device.

[0114] In some embodiments, the system also includes: a first control device 08, connected to the hydraulic fracturing construction device 04, for determining whether the expansion radius of at least one formation fracture reaches a preset target radius, and when it is determined that the expansion radius reaches the target radius, the first control device sends a second control instruction to the hydraulic pressure construction device indicating to stop injecting fracturing fluid, so that the hydraulic fracturing construction device stops hydraulic fracturing construction.

[0115] In some embodiments, the first control device 08 specifically includes:

[0116] A first calculation module 082 is configured to calculate a three-dimensional shape of a formation fracture based on a pre-built hydraulic fracturing model, rock mechanical properties, and first construction parameters, and to obtain an expansion radius of the formation fracture based on the three-dimensional shape;

[0117] The first judgment module 084 is used to judge whether the expansion radius of the formation fracture is equal to or greater than the target radius, and when it is judged that the expansion radius of the formation fracture is equal to or greater than the target radius, a second control instruction indicating to stop injecting the fracturing fluid is generated and sent to the hydraulic pressure construction device to make the hydraulic fracturing construction device stop the hydraulic fracturing construction.

[0118] In some embodiments, the hydraulic fracturing model may adopt a two-dimensional PKN model, a KGD model, a RADIAL model, a pseudo-three-dimensional model, and a full three-dimensional model. The first construction parameter is the construction parameter of the surface facilities (i.e., the injection equipment in the hydraulic fracturing construction device), including: the injection rate of the fracturing fluid, the total injection volume, and the viscosity of the fracturing fluid.

[0119] In some embodiments, the system also includes: a second control device 10, connected to the injection device 06, for determining whether the width of at least one formation fracture is equal to or greater than a preset target width. If so, a third control instruction indicating to stop injecting high-pressure fluid is generated and sent to the injection device 06, so that the injection device 06 stops injecting high-pressure fluid into at least one formation fracture, so that the width of the formation fracture remains unchanged.

[0120] In some embodiments, the second control device 10 is also used to monitor whether the power supply of the injection device 06 is sufficient. If not, a third control instruction indicating to stop injecting high-pressure fluid is generated and sent to the injection device 06, so that the injection device 06 stops injecting high-pressure fluid into at least one formation fracture, so that the width of the formation fracture remains unchanged.

[0121] Specifically, in some embodiments, the injection device 06 is installed in an injection pipeline (i.e., a pipeline connecting the water reservoir and the wellbore and for fluid injection). When the injection device 06 stops injecting high-pressure fluid into at least one formation fracture, the injection device 06 puts the injection pipeline into a closed state / non-circulating state. Specifically, the injection device 06 closes the valve in the injection pipeline.

[0122] In some embodiments, the system further includes: a power generation device 12 for converting elastic deformation energy of formation rock into electrical energy under the action of high-pressure fluid when high-pressure fluid in at least one formation fracture is reversed under the action of rock squeezing.

[0123] In some embodiments, the system further includes a water reservoir 14 connected to the injection device 06 for storing fluid.

[0124] Furthermore, in some embodiments, the water reservoir and the wellbore corresponding to the formation fracture are connected through a reverse flow pipe, and a control valve for controlling the opening (i.e., circulation) or closing (i.e., no circulation) of the wellbore or the reverse flow pipe is provided in the wellbore or the reverse flow pipe. Accordingly, the system also includes: a monitoring device, connected to the control valve, for monitoring whether there is a demand for power generation. When a demand for power generation is detected, a first control instruction indicating the opening of the control valve of the reverse flow pipe is generated and sent to the control valve to control the opening of the control valve, that is, to connect the water reservoir and the wellbore. Otherwise, the monitoring of whether there is a demand for power generation continues.

[0125] Specifically, in some embodiments, the reverse flow pipe between the water reservoir and the wellbore is normally in a closed state / non-flowing state (specifically, the valve in the reverse flow pipe is normally in a closed state). When the power generation device 12 receives a first control instruction sent by a monitoring device indicating to open the control valve corresponding to the reverse flow pipe (for example, a control instruction from a power grid or other control system connected to the power generation device 12, or a control instruction issued by a staff member), the power generation device 12 will open the reverse flow pipe between the wellbore and the water reservoir (specifically, open the control valve corresponding to the reverse flow pipe), so that under the action of rock squeezing, the high-pressure fluid in the formation fracture is reversed into the water reservoir through the reverse flow pipe, and drives the impeller of the power generation device 12 to rotate to generate electricity. If the power generation device 12 does not receive a control instruction indicating to open the control valve of the reverse flow pipe, the power generation device 12 always keeps the reverse flow pipe closed. At this time, the monitoring module continues to monitor whether there is a power supply demand. Of course, in other embodiments, the staff can determine whether there is a power supply demand and control the opening and closing of the valve in the injection / reverse flow pipe by themselves.

[0126] In some embodiments, the injection device 06 comprises:

[0127] a fluid injection module 062 for injecting high-pressure fluid into at least one formation fracture;

[0128] The pressure monitoring module 064 is used to monitor the pressure of the injected fluid in real time;

[0129] The pressure judgment module 066 is connected to the fluid injection module 062 and the pressure monitoring module 064, and is used to determine whether the pressure of the injected fluid is greater than the minimum principal stress of the energy storage formation and less than the expansion pressure of the formation fracture. If so, the pressure judgment module 066 does nothing. Otherwise, the pressure judgment module 066 generates a fourth control instruction indicating adjustment of the second construction parameter (i.e., the working parameter of the fluid injection module 062) and sends it to the fluid injection module 062 to control the fluid injection module 062 to adjust the second construction parameter so that the current fluid pressure is always maintained between the expansion pressure and the minimum principal stress of the energy storage formation.

[0130] Preferably, in order to simplify the system, in some embodiments, the power generation device 12 and the fluid injection module 062 of the injection device 06 are the same device, that is, the injection pipeline and the reverse flow pipeline are the same pipeline. For example, in some embodiments, there is no need to set up a power generation device 12 in the system, wherein the fluid injection module 062 is set in the pipeline connecting the water reservoir 14 and the wellbore. When power is supplied to the injection device 06 and the fluid injection module 062 is turned on, the fluid injection module 062 drives the fluid in the water reservoir 14 into the formation fracture. At this time, the fluid injection module 062 (that is, the power generation device 12) keeps the pipeline between the water reservoir and the wellbore closed. When a power generation demand is detected, the fluid injection module 062 (that is, the power generation device 12) receives a control instruction indicating the power supply demand sent from the outside, and then the fluid injection module 062 opens the pipeline connecting the water reservoir and the wellbore, so that the high-pressure fluid in the formation fracture is reversed through the pipeline to the water reservoir 14 under the action of rock compression, and drives the impeller of the fluid injection module 062 set in the pipeline to rotate and generate electricity.

[0131] Example 5

[0132] A third aspect of the present invention is to provide a non-temporary computer program product, which stores a computer program. When the computer program is executed by a processor, the device where the computer program product is located is controlled to execute the steps of the method described in Example 1.

[0133] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0134] Reference to "one embodiment" or "an embodiment" of the present invention means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The phrase "in one embodiment" appearing in different places does not necessarily refer to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Furthermore, the terms "one" and "an" are not used herein to indicate a limitation on quantity, but rather to indicate the presence of at least one referenced item. Furthermore, various features are described that may be exhibited by some embodiments but not by other embodiments. Similarly, various requirements are described that may be requirements of some embodiments but not of other embodiments.

[0135] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for storing and releasing energy through formation fractures, characterized in that: Including steps: Identify at least one reservoir formation that does not contain oil or gas; Preset target radius and target width of formation fractures; Performing hydraulic fracturing on the energy storage formation to generate at least one formation fracture in the energy storage formation; obtaining an expansion radius of a formation fracture, determining whether the expansion radius is equal to or greater than a target radius, and stopping hydraulic fracturing construction when the expansion radius of the formation fracture is equal to or greater than the target radius; Obtain the minimum principal stress of the formation and the expansion pressure of the formation fracture; Using electrical energy to drive an injection device to inject a high-pressure fluid into the at least one formation fracture, thereby increasing the width of the formation fracture; wherein the fluid pressure of the high-pressure fluid is always maintained to be greater than the minimum principal stress of the formation and less than the expansion pressure of the formation fracture, so that the width of the formation fracture gradually increases, while the expansion radius remains unchanged or constant; determining whether the width of at least one of the formation fractures is equal to or greater than a preset target width, and if so, causing the injection device to stop injecting the high-pressure fluid into the at least one formation fracture, and maintaining the width of the formation fracture unchanged in a manner that maintains the current bottom hole pressure; The high-pressure fluid discharged during the closure of the formation fracture is used to drive a preset power generation device to generate electricity to release energy.

2. The method according to claim 1, characterized in that The expansion pressure of formation fractures is obtained by analyzing the instantaneous shut-in pressure of the pressure drop curve after pumping is stopped during hydraulic fracturing operation.

3. The method according to claim 1, characterized in that Monitor the fluid pressure of the injected high-pressure fluid in real time and determine whether the fluid pressure injected into the formation fracture is greater than the minimum principal stress of the formation and less than the expansion pressure of the formation fracture; if so, maintain the second operation parameter for injecting the high-pressure fluid into the formation fracture; otherwise, adjust the second operation parameter for injecting the high-pressure fluid into the formation fracture so that the fluid pressure in the current formation fracture is always maintained between the expansion pressure and the minimum principal stress of the energy storage formation; The second construction parameters include: fluid injection rate and total injection volume.

4. The method according to claim 1, wherein The three-dimensional shape of the formation fracture is calculated based on the hydraulic fracturing model, rock mechanical properties and the first construction parameter, and the expansion radius of the formation fracture is obtained based on the three-dimensional shape.

5. The method according to claim 1, wherein The fracturing fluid used in the hydraulic fracturing construction includes a fluid loss agent, which includes: at least one high molecular polymer, and / or at least one resin, and / or at least one quartz sand, and / or at least one gel, and / or at least one silicate, and / or at least one sulfate, and / or at least one phosphate, and / or at least one oxalate, and / or at least one particle having the effect of plugging the pores of the rock matrix of the formation.

6. The method according to claim 1, characterized in that Before injecting high-pressure fluid into the at least one formation fracture, the method further includes the step of setting at least one water reservoir underground or on the ground for storing the fluid.

7. The method according to claim 1, characterized in that The step of utilizing the high-pressure fluid discharged during the closure of the formation fracture to drive a preset power generation device to generate electricity specifically comprises the following steps: Monitor whether there is a demand for power generation, and when it is detected that there is a demand for power generation, open the control valve on the reverse flow pipe connecting the wellbore corresponding to the formation fracture to the ground, so that the high-pressure fluid in the formation fracture is reversed to the ground through the reverse flow pipe and drives the power generation equipment to generate electricity; otherwise, continue to monitor whether there is a demand for power generation.

8. The method according to claim 1, characterized in that The high-pressure fluid includes: a bactericide, and / or a descaling agent, and / or a mineral salt, and / or a fluid loss control agent.

9. A system for implementing the method for storing and releasing energy through formation fractures according to any one of claims 1 to 8, characterized in that: include: a formation identification device for identifying at least one energy storage formation that does not contain oil or gas; A hydraulic fracturing construction device, used for performing hydraulic fracturing construction on the energy storage formation, so that at least one formation fracture is generated in the energy storage formation; an injection device for injecting high-pressure fluid into the at least one formation fracture to increase the width of the at least one formation fracture, thereby converting electrical energy into elastic deformation energy of the formation rock for storage; A power generation device is used to convert the elastic deformation energy of the formation rock into electrical energy under the drive of the high-pressure fluid when the high-pressure fluid in the formation fracture is reversed under the action of rock compression during the closing process of the formation fracture.

10. The system according to claim 9, characterized in that Also includes: A water reservoir for storing the high-pressure fluid, wherein the water reservoir is connected to the wellbore corresponding to the formation fracture via a reverse flow pipe, and a control valve is provided in the wellbore or the reverse flow pipe; A monitoring device is connected to the control valve and is used to monitor whether there is a current demand for power generation. When a demand for power generation is detected, a first control instruction indicating opening the control valve is generated and sent to the control valve, so that the wellbore is connected to the water reservoir through the reverse flow pipe; otherwise, the monitoring device continues to monitor whether there is a demand for power generation.

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